rr^ 



382 PROCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 



of a plant. The tunnel goes downwards and opens on the side a little 

 way down from the top. The larva pupat es near the mouth of this 

 opening through which the moth emerges. There is always a single 

 larva in one plant. 



The effect of attack by the larva is always disastrous to the plant. 

 Further growth is stopped in every case. Only very vigorous plants, 

 whether young or old, can and do give out sideshoots or branches. In 

 the case of grown-up plants it has been assumed that they give out 

 branches so that the top becomes bunchy. But actually this happens 

 in the case of only a very small proportion of such plants, as will appear 

 from the facts stated below. Between the 3rd and 4th August, fifty 

 affected plants of Satin No. 131 with stems (actual canes measured below 

 the base of the whorl of leaves at the top) varying in height from 

 1' 4" to 3' 10" were marked. From half of them the " dead heart " leaf 

 was pulled out with the hand and these we may call Lot I, and the 

 rest Lot IL The height of all was measured at intervals and none of 

 them except one in Lot I was observed to grow. On the 23rd October, 

 nine in Lot I and twelve in Lot II were observed to have given out 

 branches and eight in Lot I and ten in Lot II were practically wholly 

 dry and all the others in process of drying from the top downwards. 

 The internal tissue of the dry and drying ones was practically wholly 

 red. The tops of those which had given out branches were also drying. 

 It was evident that hardly any of them would contribute to the harvest. 

 The one in Lot I which was growing measured 3' 2" when marked on 

 4th August and 7' 4" on the 23rd October. It was afterwards chewed 

 and damaged by a jackal. The same effect as recorded in these two 

 lots is observable in mature canes but, as they are harvested soon, they 

 have hardly time to dry. 



Scirpojphaga xanthogastrella occurs commonly in the three foodplants 

 mentioned but more in Jcanra than in either of the other two. In the 

 Purple Mauritius sugarcane plot in Chamiia in 1917 the caterpillaBS 

 appeared very early in April. But in about 8 acres of different varieties 

 of cane in Jhilli and Brickfield in 1918 even on the 6th May there were 

 hardly any observable, a search through the whole fields revealing only 

 one caterpillar, though at a distance of about half-a-mile they were 

 occurrmg plentifully in kanra. 



Scirpophaga monostigma. (Plate 42, fig. 2.) 

 Foodplant — Sugarcane. 



This is similar io S. xantJwgastrella m habit. The larval- and pupal 

 forms of these two species are indistinguishable. The moth of S. monos- 

 tigma is however distinguishable as it has a black spot on the fore- wing. 



